Indian Journal of Animal Research

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Influence of in situ Biofloc Production on Bio Growth Performance, Physiological Immune Response, Digestive Enzyme Activity, Nutrient Composition and Disease Resistance of Etroplus suratensis 

A. Jackqulinwino1, B. Ahilan1, Cheryl Antony1, P. Chidambaram1, A. Uma1, P. Ruby1,*
1Tamil Nadu Dr. J. Jayalalithaa Fisheries University, Nagapattinam, Dr. M.G.R. Fisheries college and Research Institute, Ponneri-601 204, Tamil Nadu, India.

Backgroud: The present experiment was conducted to investigate the effects of insitu jaggery based biofloc on biogrowth performance, physiological immuno response, digestive enzyme activity, nutrient composition and disease resistance of Etroplus suratensis.

Method: The fingerlings of pearlspot, E. suratensis with an average body weight of 5.67±0.08 g was stocked at the rate of 150/m3 in treatment and control system. The insitu biofloc was produced in 2.4 ton capacity outdoor tanks using jaggery as carbon source at two different C: N ratio of viz, 10: 1 (B1) and 20:1 (B2), where clear brackishwater system and without carbon source as control.

Result: The levels of ammonia nitrogen, nitrite–nitrogen and nitrate–nitrogen were reduced in the insitu biofloc compared to control while TSS and TS were increased significantly in all insitu biofloc compared to control.  The physiological immuno responses such as Respiratory burst test, Myeloperoxidase, serum lysozyme and antioxidant enzymes activity Superoxide dismutase  and catalase were found to be significantly higher in B2 at end of the trial. Stress parameters glucose and cortisol were significantly lower in jaggery based biofloc system especially in (B2) C: N 20:1 compared to control. The fishes from the jaggery based biofloc groups possessed significantly (P<0.05) higher immune status as compared to control. The digestive enzymes activity such as amylase protease and lipase, of fish was higher in biofloc treatment and lower in control. Compare to control the nutrient composition of E. suratensis was significantly higher in the treatment groups. Moreover, jaggery based insitu fishes showed the lower cumulative mortality rate and Enhanced relative levels of protectio after experimental challenge with A. hydrophila compared to control.

Aquaculture has become one of the fastest-growing food producing sectors. In 2020, production from aquaculture reached 87.5 million tonnes and in that 66% of world fish production was consumed as food (FAO, 2022). The demand for aquatic food is increasing as it has proved to be an option to cope with the world food demand even though there are lot of criticisms arising in this sector due to overutilization of water resources, degradation of natural ecosystem, salinization and acidification of soils, environmental impacts such as eutrophication and nitrification due to effluents discarded into the natural water bodies. To overcome these bottlenecks, adoption of advanced culture methods with a sustainable intensification is needed for Aquaculture sector. The recent advanced “Biofloc Technology” could be a potential and sustainable alternative that can reduce environmental impacts with zero water exchange, less feed input while increasing stocking density and hence the production and crop yield. The external addition of carbon sources to the culture water stimulates the growth of heterotrophic bacteria and its uptake of nitrogen by the production of the microbial protein (Avnimelech, 1999) faster than regular nitrification process (Hargreaves, 2006). The carbon source will trigger the heterotrophic bacterial population by promoting the nitrogen uptake through the production of microbial protein and more rapidly decreases the ammonium concentration (Kasan et al., 2015). The selection of carbon source may depend on the accessibility and digestibility of carbohydrates, protein content and cost-effectiveness (Khanjani et al., 2017). However, few studies have been carried out on freshwater fishes like Tilapia (Azim et al., 2008; Ekasari et al., 2015; Long et al., 2015; Perez-Fuentes et al., 2013; Menaga et al., 2019; Elayaraja et al., 2020). Diversification of aquaculture species can be achieved by the exploitation of new cultured species that offers both biological and economic benefits. Pearlspot, Etroplus suratensis, known locally as ‘Karimeen’ is the largest among Indian cichlids. It is a high-valued food fish endemic to peninsular India and Sri Lanka (Munro, 1955). Keeping in view the above factors, the present study aimed to evaluate the jaggery based biofloc on the bio growth performance, physiological immune response, digestive enzyme activity, nutrient composition and disease resistance of Etroplus suratensis reared in in situ biofloc system.
The experiment was conducted in the Pulicat Research Farm Facility, Pazhaverkadu, Ponneri. This study was approved by ethical committee of Tamil Nadu Dr. J. Jayalalithaa Fisheries University, Nagapattinam, Tamil Nadu, India.
Experimental design
The experiment was conducted in the nine outdoor biofloc unit tanks (2.4-ton capacity) with completely randomized design (CRD). The advanced fingerlings of Pearl sport (Etroplus suratensis) were used for the experimental study were collected from Pulicat lake, Pazhaverkadu and disinfected with KMnO4 and stocked in 30 ppt brackish water. The fishes were slowly acclimatized to 22 to 25 ppt by adding freshwater. Pearlspot fingerlings weighing 5.68 to 5.79±0.01 g was stocked at the rate of 150/m3. The development of in situ Biofloc within the system and carbon addition was carried out based on the protocol described by Avnimelach 2009. Development of floc was triggered with continuous aeration with help of the air compressor. The tanks were left for 15 days to make it favorable for the growth of microbes to develop the bio floc. Strong aero tube aeration was made to keep floc in constant suspension. These biofloc production tanks were monitored regularly for two different ratios of C:N (10:1) B1 and (20:1) B2 maintained by adding jaggery on the rate of ammonia Nitrogen content of water. Clear brackish water system used for control (C). Fishes were fed with 3 to 5% of body weight. The feeding ration was divided into three equal quantities and given thrice a day viz., 10.00 am, 2.00 pm and 5.00 pm, while the insitu biofloc B1and B2 fishes were fed to apparent satiety. Protocol for the development of in situ jaggery based Biofloc in the FRP tank were given in Table 1.

Table 1: Protocol for the development of insitu jaggery based biofloc in the FRP tank.

Growth parameters and survival
To calculate the bio growth parameters, including the beginning and final growth rates, the absolute and specific growth rates and the feed utilization factors (FER, FCR, PER, BWI and FCE), sampling was carried out every two weeks. The growth parameters in question were computed.
Water quality parameters
Water temperature and dissolved oxygen (DO) in each tank were measured three times a day using a digital thermometer and DO meter respectively. Weekly ammonium (NH4+), nitrite (NO2-), pH, conductivity, TDS, total alkalinity, total hardness, magnesium hardness and calcium hardness were analyzed as per (APHA, 2005) procedure.
Nutrient composition of insitu jaggery based biofloc reared E. suratensis
To determine the whole-body nutrient composition of Pearlspot fingerlings the fishes were cut into pieces, minced, homogenized and immediately frozen until further analysis and the proximate analysis was determined using (AOAC, 1995) method.
Digestive enzyme activity
Protease activity (Moore and Stein, 1948) and lipase activity (Cherry and Crandell, 1932) methods were largely modified to yield amylase activity (Rick and Stegbauer, 1974).
Physiological immuno parameters
The Superoxide Dismutase activity was estimated following the modified method of Mishra and Fridovich, (1978). Catalase activity was estimated according to the method of Takahara et al., (1960). The serum glucose and cortisol level in the serum using the Semi-automatic blood biochemical analyzer Alpha technologies instrument (Alpha chem. 100i). For the total Cholesterol analysis the serum and ferric chloride was taken in a test tube and incubated at room temperature for a period of 10 min and centrifuged at 3000 rpm and the OD was measured at 560 nm by adding sulphuric acid to the supernatant The total triglycerides were measured using an auto-analyser (MERCK Selectra, Germany).
Disease resistance against Aeromonas hydrophilla
At the end of insitu experimental days of culture, the experimental fishes were challenged with Aeromonas hydrophila pathogen obtained from State Referral Laboratory under TNJFU. The isolate grown in tryptic soy broth (TSB Hi Media) for 24 h (30-31oC) was centrifuged at 10000 rpm for 10 min followed by pellet resuspension in phosphate buffered saline (PBS, pH 7.2). The suspension in sterile PBS was injected intramuscularly (0.1ml) in healthy Etroplus suratensis from all the treatments delivering 107 CFU/fish. Following the challenge, the fishes were observed for mortality every day for up to 14 days and the cumulative mortality was recorded.  The relative level of protection (RLP) was calculated as:
Data analysis
Statistical analysis of bio growth and other parameters were analysed by one-way analysis of variance (ANOVA) using SPSS, 20.0. Duncan’s multiple range tests was used for post hoc comparison of mean (P<0.05) and statistical significance for the test was set at P<0.05 between different groups.
Growth performances and feed utilization
Growth performances and feed utilization parameters of E. suratensis after 90 days of growth trial are given in Table 2. The final body weight of the insitu biofloc B1 and B2 fishes differed significantly with highest growth 53.26±0.18 and 57.90±0.06 respectively. The better feed utilization in terms of FCR (0.55±0.01), FER (1.83±0.01) and PER (1.93±0.01) were observed in (B2) compared to control and (B1). The insitu biofloc reared fishes obtained higher survival rate compared to control. The highest biomass was observed in B2 (8260.97±0.05 g) and the lowest biomass was observed in control (5630.08 ± 0.05 g).  The earlier studies reported that Biofloc technology (BFT) improves growth performance and feed utilization of cultured fish (Hari et al., 2004; Azim and Little, 2008; Kuhn et al., 2009; Ahmad et al., 2017; Luo et al., 2014; Zhang et al., 2016). Previous studies concluded that insitu floc in various carbon sources served as an incremental food which continuously provide additional protein (EAA), polyunsaturated fatty acids, vitamins and minerals (Avnimelech, 1999; Avnimelech, 2007; Azim and Little, 2008; De Schryver et al., 2008; Luo et al., 2014).

Table 2: Biogrowth and Feed utilization of in situ jaggery based biofloc reared E. suratensis.

Water quality parameters in in situ biofloc system
Water quality parameters were measured throughout the in situ biofloc culture period as shown in Table 3. The temperature varied slightly throughout the in situ floc production system and control tank further it varied between 26.5-31°C. DO concentration in insitu biofloc tanks (B1 and B2) was within a range of 4.4-6.8 mg/l and did not show much variation throughout the experimental period, but it did fluctuate slighlty with increased biodiversity of floc associated organisms. While in control group, DO was in the range of 6.1-7.1 mg/l due to continuous exchange of water. In comparison to the control, the CO2 detected in the in situ treatments was considerably (P<0.01) greater. Water pH was in the range of 8.3 to 8.5 in all in situ biofloc production tank and 7 to 8 in control tank. Significantly (P<0.05) higher pH was observed in B1 and B2 than control. During the culture period ammonia concentration was in range of 0.001 to 0.008 mg/l in insitu biofloc and 0.01 to 0.020 mg/l in control. Lower concentration of ammonia was observed in in situ biofloc than control. Nitrite- ´100 nitrogen concentration was significantly (P<0.05) lower in treatments than control. The results of the water quality parameters on biofloc development with the jaggery as a carbon source was agreed well with findings of Sakkaravarthi et al., 2015; Ruby et al., 2022; Elaiyaraja et al., 2020; Susitharan et al., 2021).

Table 3: Water quality parameters during the culture period of 90 days.

Digestive enzyme activity
The digestive enzymes viz, amylase, protease and lipase activity were significantly affected by biofloc produced by insitu manner. The results of digestive enzyme analysis were given in Table 4. Biochemical composition of the diet plays an important role in the digestive enzyme profile of fish and shrimp. The specific activity of digestive enzymes was significantly (P<0.05) improved in the current study when compared to control B2 and B1. Treatment B2’s increased digestive enzyme activity may have improved digestion and nutrition absorption, as evidenced by this group’s much greater (P<0.05) growth rate. The study by Xu and Pan (2012) in biofloc based system reported the similar results in P. vannamei. Growing performance may be enhanced by greater nutrient consumption brought about by higher digestive enzyme activity (Ezhilarasi et al., 2019). Similarly, an enhanced digestive enzyme activity was reported in L. vannamei Xu and Pan (2012), P. monodon (Anand et al., 2013).

Table 4: Digestive enzyme activity of E. suratensis reared in jaggery based biofloc system.

Nutrient composition (% wet basis) of Etroplus suratensis
The whole-body nutrient composition of E. suratensis such as protein, lipid and ash are shown in Table 5. The highest crude protein in fish body was found in B2 (20.97±0.07) which differed significantly with C (15.43±0.27). The highest crude lipid recorded was (3.34±0.11) in B1, followed by B2 (3.21±0.05). Similar results with enriched nutritional value were also reported by Ray et al., (2011); Xu and Pan (2012) reported that differences in proximate composition may affect nutritional value, sensory qualities and shelf-life of the fish.

Table 5: Nutrient composition (% Wet basis) of Etroplus suratensis reared in in situ biofloc system.

Physiological immuno parameters of Etroplus suratensis
In the present study, fishes reared in insitu biofloc treatments, the non-specific immune parameters NBT, serum lysozyme, myeloperoxidase (Fig 1,2,3) showed higher values as compared to control. Biofloc reduced the physiological stress in GIFT which agrees with the studies of Verma et al., (2016) who reported the reduced levels of Cortisol and Glucose (Table 5) in Labeo rohita when reared in biofloc systems. SOD and Catalase are two important enzymes in the cellular antioxidant defence system, dealing with oxidative stress. Lower levels of SOD and Catalase are indication for cell damage due to the accumulation of the high-level of free radical affecting the heath of fishes. The results from the present study revealed that the supplementation of insitu biofloc increased SOD (Fig 5) and catalase (Fig 4) level in insitu Etroplus suratensis than control. Similar studies were done by Ruby et al., (2022); Menaga et al., (2019) and Elaiyaraja et al., (2020). Increased bacterial pathogen killing ability of phagocytes can be inferred from increased respiratory burst activity which is a most important bactericidal mechanism in fishes. Verma et al., (2016) observed an improvement in the immune parameters of Rohu fingerlings grown in tapioca-based biofloc. This could be connected to the fact that the culture animals’ consumption of biofloc improves their nutrition and activates the fish’s cellular defense mechanisms through phagocytosis and respiratory burst.

Fig 1: Respiratory burst activity (OD at 540 nm) of E. suratensis reared in in situ jaggery based biofloc system.

Fig 2: Myeloperoxidase activity (OD at 640 nm) of E. suratensis reared in insitu jaggery based biofloc system.

Fig 3: Lysozyme activity (µg/ml) of E. suratensis reared in in situ jaggery based biofloc system.

Fig 4: Catalyse (U/ mg protein) of E. suratensis reared in in situ jaggery based biofloc system.

Fig 5: Superoxide dismutase activity (U/ mg protein) of E. suratensis reared in insitu jaggery based biofloc system.

Disease resistance against Aeromonas infection of Etroplus suratensis reared in in situ biofloc system
In this study, fish injected with sterile saline (C-ve) showed no mortalities or pathological lesions, while those challenged with A. hydrophila displayed pathological alteration on the third day post infection. The cumulative mortality rate (Fig 6) was considerably lower in the insitu biofloc groups than control and the maximum relative protection (Table 6) was recorded in the B2, it was noted that all control fish died within 3-5 days post-challenge, while in situ biofloc reared fish required a long time 5 to 9 days. The major organ manifestations were observed with the higher degree of infection in control (Abraham et al., 2007). Since heterotrophic bacteria in the biofloc, created in the culture system produced immunostimulatory chemicals, the infection in B2 and B2 fish was shown to be less severe.


Table 6: Mortality percentage and RLP percentage of Etroplus suratensis reared in in situ jaggery based biofloc system with control.

From the present study, it is concluded that when the pearlspot is reared in the in situ biofloc system with jaggery as a carbon source an enhanced growth rate and immune response was observed. Therefore, the application of this technology may be helpful in aquaculture to promote the growth and immunity of the E. suratensis. With C: N 20: groups thought to be more suitable for pearlspot culture, this work has provided a good understanding of the insitu jaggary based biofloc system.
The authors are thankful to the Dean, Dr. M.G.R. Fisheries College and Research Institute, Tamil Nadu Dr. J. Jayalalithaa Fisheries University, Ponneri 601 204, Tamil Nadu, India for rendering the facilities to conduct the present study.
Every step taken was compliant with the responsible parties’ ethical standards, the authors declare that they have no conflict of interest.

  1. Ahmad, I., Rani, A.M.B., Verma, A.K. and Maqsood, M. (2017). Biofloc technology: An emerging avenue in aquatic animal healthcare and nutrition. Aquaculture International. 25: 1215-1226.

  2. Abraham, T.J., Babu, C.H.S., Mondal, S., Banerjee, T. (2007). Effects of dietary supplementation of commercial human probiotic and antibiotic on the growth rate and content of intestinal microflora in ornamental fishes. Bangladesh J. Fish. Res. 11: 57-63.

  3. Anand, P.S.S., Kohli, M.P.S., Dam Roy, S., Sundaray, J.K., Kumar, S., Sinha, A., Pailan, G.H., Sukham, M.K. (2013b). Effect of dietary supplementation of periphyton on growth performance and digestive enzyme activities in Penaeus monodon. Aquaculture. 392(395): 59-68.

  4. AOAC, (1995). Official Methods AOAC, 1995. Official Methods of Analysis, 13th(ed). Association of Official Analytical Chemist, Washinton D.C.

  5. APHA, (2005). Standard Methods for the Examination of the Water and Wastewater, 22nd Edition. American Public Health Association, Washington, D.C.

  6. Avnimelech, Y. (1999). Carbon/Nitrogen ratio as a control element in aquaculture systems. Aquaculture. 176(3-4): 227-235.

  7. Avnimelech, Y. (2007). Feeding with microbial flocs by tilapia in minimal discharge bioflocs technology ponds. Aquaculture. 264(1-4): 140-147.

  8. Azim, M.E., Little, D.C. and Bron, J.E. (2008). Microbial protein production in activated suspension tanks manipulating C/N ratio in feed and implications for fish culture. Bioresour.  Technol. 99(9): 3590-3599.

  9. Cherry, L.S., Crandal, L.A. (1932). The specificity of pancreatic lipase; Its appearance in the blood after pancreatic injury. Am. J. Physiol. Leg. Cont. 100(2): 266-273.

  10. De Schryver, P., Crab, R., Defoirdt, T., Boon, N. and Verstraete, W. (2008). The basics of bio-flocs technology: The added value for aquaculture. Aquaculture. 277(3-4): 125-137

  11. Ekasari, J., Rivandi, D.R., Firdausi, A.P., Surawidjaja, E.H., Zairin, J.M., Bossier, P., De Schryver, P. (2015). Biofloc technology positively affects Nile tilapia (Oreochromis niloticus) larvae performance. Aquaculture. 441: 72-77.

  12. Elayaraja, S., Mabrok, M., Algammal, A., Sabitha, E., Rajeswari, M.V., Zágoršek, K., Ye, Z., Zhu, S. and Rodkhum, C. (2020). Potential influence of jaggery-based biofloc technology at different C: N ratios on water quality, growth performance, innate immunity, immune-related genes expression profiles and disease resistance against Aeromonas hydrophila in Nile tilapia (Oreochromis niloticus). Fish and Shellfish Immunology. 107(Pt A): 118-128.

  13. Ezhilarasi, V., Verma, A.K., Rani, A.M.B., Harikrishna, V., Chandrakant, M.H., Ahmad, I. and Nageswari, P. (2019). Effect of different carbon sources on growth, non-specific immunity and digestive enzyme activity of amur carp (Cyprinus rubrofuscus Lacepede 1803) fingerlings in biofloc based rearing system using inland saline groundwater. Indian Journal of Fisheries. 66(3): 87-94.

  14. FAO, (2022). The State of World Fisheries and Aquaculture 2020. Towards Blue Transformation. Rome, FAO.  

  15. Hargreaves, J.A. (2006). Photosynthetic suspended-growth systems in aquaculture. Aquacultural Engineering. 34(3): 344- 363.

  16. Hari, B., Kurup B.M., Varghese J.T., Schrama J.H. and Verdegem M.C.J. (2004). Effects of carbohydrate addition on production in extensive shrimp culture system. Aquaculture. 241: 179-194.

  17. Kasan, N.A., Said, S.M., Ghazali, N.A., Hashim, N.F.C., Ibrahim, Z. and Amin, N.M. (2015). Application of biofloc in aquaculture: An evaluation of flocculating activity of selected bacteria from biofloc. Beneficial Microorganisms in Agriculture, Aquaculture and Other Areas. Springer. 165-182 pp.

  18. Khanjani, M.H., Sajjadi, M.M., Alizadeh, M. and Sourinejad, I. (2017). Nursery performance of Pacific white shrimp (Litopenaeus vannamei Boone, 1931) cultivated in a biofloc system: The effect of adding different carbon sources. Aquaculture Research. 48: 1491-1501.

  19. Kuhn, D.D., Boardman, G.D., Lawrence, A.L., Marsh, L., Flick, G.J. (2009). Microbial floc meal as a replacement ingredient for fish meal and soybean Protein in shrimp feed. Aquaculture. 296: 51-57.

  20. Long, L., Yang, J., Li, Y., Guan, C. and Wu, F. (2015). Effect of biofloc technology on growth, digestive enzyme activity, hematology and immune response of genetically improved farmed tilapia (Oreochromis niloticus). Aquaculture. 448: 135-141.

  21. Luo, G., Gao, Q., Wang, C., Liu, W., Sun, D., Li, L. and Tan, H. (2014). Growth, digestive activity, welfare and partial cost- effectiveness of genetically improved farmed tilapia (Oreochromis niloticus) cultured in a recirculating aquaculture system and an indoor biofloc system. Aquacult. 422: 1-7.

  22. Menaga, M., Felix, S., Charulatha, M., Gopalakannan, A. and Panigrahi, A. (2019). Effect of in situ and ex situ biofloc on immune response of genetically improved farmed tilapia. Fish and Shellfish Immunology. 92: 698-705.

  23. Mishra, H.P. and Fridovich, I. (1978). Inhibition of superoxide dismutases by azide. Archives of Biochemistry and Biophysics. 189(2): 317-322.

  24. Moore, S., Stein, W.H. (1948). Photometric ninhydrin method for use in the chromatography of amino acids. J. Biol. Chem. 176: 367-388.

  25. Munro, I.S.R. (1955). The Marine and Freshwater Fishes of Ceylon. Dept. External Affairs, Canberra, 351 p., 56pls 1967. The Fishes of New Guinea. Dept. Agric., Stock and Fish. Port Moresby New Guinea. 650.

  26. Perez-Fuentes, J.A., Perez-Rostro, C.I. and Hernandez-Vergara, M.P. (2013). Pond-reared Malaysian prawn Macrobrachium rosenbergii with the biofloc system. Aquaculture. 400: 105-110.

  27. Ray, A.J., Dillon, K.S. and Lotz, J.M. (2011). Water quality dynamics and shrimp (Litopenaeus vannamei) production in intensive, mesohaline culture systems with two levels of biofloc management. Aquacultural Engineering. 45(3): 127-136.

  28. Rick, W., Stegbauer, H.P. (1974). a-Amylase Measurement of Reducing Groups. In: Methods of Enzymatic Analysis (ed. Bergmeyer, H.V.), 2nd edn, Vol, 2, Academic Press, Newyork, pp. 885-889.

  29. Ruby, P., Ahilan, B., Antony, C., Manikandavelu, D., Selvaraj, S. and Moses, T.L.S. (2022). Evaluation of effect of the different stocking densities on growth performance, survival, water quality and body indices of pearlspot (Etroplus suratensis) fingerlings in biofloc technology. Indian Journal of Animal Research. 56(8): 1034-1040. doi: 10.18805/ IJAR.B-4922.

  30. Sakkaravarthi, K. and Sankar, G. (2015). Identification of effective organic carbon for biofloc shrimp culture system. Journal of Biological Sciences. 15(3): 144-149.

  31. Susitharan, V., Rajagopalsamy, C.B.T., Sindhu, C., Mary, S.J.A.J. and Dinesh, R. (2021). Effect of biofloc technology with different carbon sources on growth performance of pearl spot Etroplus suratensis under flow through system. Biological Forum-An International Journal. 14(1): 224-233.

  32. Takahara, S., Hamilton, H.B., Neel, J.V., Kobara, T.Y., Ogura, Y. and Nishimura, E.T. (1960). Hypocatalasemia: A new genetic carrier state. The Journal of Clinical Investigation. 39(4): 610-619.

  33. Verma, A.K., Rani, A.B., Rathore, G., Saharan, N. and Gora, A.H. (2016). Growth, non-specific immunity and disease resistance of Labeo rohita against Aeromonas hydrophila in biofloc systems using different carbon sources. Aquaculture. 457: 61-67.

  34. Xu, W.J. and Pan, L.Q. (2012). Effects of bioflocs on growth performance, digestive enzyme activity and body composition of juvenile Litopenaeus vannamei in zero-water exchange tanks manipulating C/N ratio in feed. Aquaculture. 356-357.

  35. Zhang, N., Luo, G., Tan, H., Liu, W. and Hou, Z. (2016). Growth, digestive enzyme activity and welfare of tilapia (Oreochromis niloticus) reared in a biofloc based system with poly-â hydroxybutyric as a carbon source. Aquaculture. 464: 710-717.

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